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为了改善激光诱导击穿光谱质量,使用具有时间分辨功能的光谱仪采集激光诱导钢靶等离子体光谱,研究了钢靶等离子体辐射光谱随延迟时间的变化特性。结果表明,光谱强度和背景强度随延时皆呈指数衰减,原子谱线强度在前4μs内衰减更快但寿命较长,离子谱线存在寿命较短;采集延时对不同谱线的信噪比影响不同,Mn I403.08nm、Cr I 428.97nm、CrⅡ458.82nm、Fe I 430.79nm和FeⅡ503.57nm谱线得到的最佳延时分别为8,2,0,2,4μs。采用双线法和Boltzmann曲线法计算等离子体温度、Saha-Boltzmann方程计算电子密度,验证了在0~10μs范围内采集到的光谱信号满足局部热平衡状态。
In order to improve the quality of laser-induced breakdown spectroscopy, a laser-induced plasma target plasma spectrum was acquired using a time-resolved spectrometer, and the variation of the emission spectrum of the steel target plasma with the delay time was studied. The results show that both the spectral intensity and the background intensity decrease exponentially with the delay time. The intensity of the atomic line decays faster but has a longer lifetime in the first 4μs, and the lifetime of the ion spectrum is shorter. The best retardation of Mn I403.08nm, Cr I 428.97nm, CrⅡ458.82nm, Fe I 430.79nm and FeⅡ503.57nm were 8,2,0,2,4μs, respectively. The plasma temperature was calculated by the two-line method and the Boltzmann curve method, and the electron density was calculated by the Saha-Boltzmann equation. It was verified that the spectral signal collected in the range of 0-10 μs satisfied the local thermal equilibrium.